Bicycle derailleur with rotation resistance and resistance control

ABSTRACT

A bicycle derailleur comprises a base member adapted to be mounted to a bicycle, a movable member movably coupled to the base member, a chain guide coupled to the movable member for rotation around a rotational axis, a resistance applying element that applies resistance to rotational movement of the chain guide, and a resistance control element. The resistance control element applies a force to the resistance applying element in a direction that is non-parallel with the rotational axis, without any manual operations, to prevent a reduction in the resistance to rotational movement of the chain guide applied by the resistance applying element.

BACKGROUND OF THE INVENTION

The present invention is directed to bicycle transmission devices and,more particularly, to a bicycle derailleur with rotation resistance.

A typical bicycle derailleur transmission includes a plurality ofsprockets that rotate together with a front crank or with a rear wheel,a chain, and a derailleur that selectively shifts the chain among theplurality of sprockets. A typical derailleur includes a base memberadapted to be mounted to the bicycle frame, a movable member movablycoupled to the base member, and a chain guide coupled to the movablemember. The chain guide engages the chain to selectively switch thechain among the plurality of sprockets when the movable member movesrelative to the base member.

The chain guide of a rear derailleur ordinarily is rotatably mounted tothe movable member and is spring-biased in a clockwise direction (whenviewed from the right side of the bicycle) so that the chain guide cantake up the slack in the chain when the chain engages thesmaller-diameter sprockets. However, during rough riding, bumps andshocks may cause the chain guide to rotate counterclockwise, therebycreating undesirable slack in the chain. To prevent this from occurring,motion resisting structures have been added to some rear derailleurs. Anexample of a motion resisting structure is disclosed in U.S. PatentApplication Publication Number 2009/0054183 A1. As shown therein, abicycle derailleur comprises a base member adapted to be mounted to abicycle, a movable member movably coupled to the base member, and achain guide coupled to the movable member. The chain guide is coupledfor rotation around a rotational axis, and a biasing element biases thechain guide in a selected rotational direction around the rotationalaxis. A resistance applying unit applies a resistance to rotationalmovement of the chain guide in a direction opposite the selectedrotational direction, and an adjusting unit adjusts an amount ofresistance applied by the resistance applying unit.

SUMMARY OF THE INVENTION

The present invention is directed to various features of a bicycletransmission. In one embodiment, a bicycle derailleur comprises a basemember adapted to be mounted to a bicycle, a movable member movablycoupled to the base member, a chain guide coupled to the movable memberfor rotation around a rotational axis, a resistance applying elementthat applies resistance to rotational movement of the chain guide, and aresistance control element. The resistance control element applies aforce to the resistance applying element in a direction that isnon-parallel with the rotational axis, without any manual operations, toprevent a reduction in the resistance to rotational movement of thechain guide applied by the resistance applying element. Additionalinventive features will become apparent from the description below, andsuch features alone or in combination with the above features and theirequivalents may form the basis of further inventions as recited in theclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a bicycle that employs a particular embodimentof a derailleur bicycle transmission;

FIG. 2 is a side view of a particular embodiment of a rear derailleur;

FIG. 3 is a front view of the derailleur shown in FIG. 2;

FIG. 4 is a side view of the movable member and chain guide detachedfrom the rest of the derailleur;

FIG. 5 is a cross-sectional view taken along line V-V in FIG. 4;

FIG. 6 is a front view of the pivot shaft and the roller clutch for thechain guide;

FIG. 7 is a perspective view of the movable member showing theresistance control lever;

FIG. 8 is a front view of the movable member when the resistance controllever is in a first position;

FIG. 9 is a side view of the movable member shown in FIG. 8 with thecover removed;

FIG. 10 is a cross-sectional view taken along line X-X in FIG. 8;

FIG. 11 is a cross-sectional view taken along line XI-XI in FIG. 6;

FIG. 12 is a perspective view of a roller retainer for the rollerclutch;

FIG. 13 is a front view of the movable member when the resistancecontrol lever is in a second position;

FIG. 14 is a side view of the movable member shown in FIG. 13 with thecover removed;

FIG. 15 is a cross-sectional view taken along line XV-XV in FIG. 13;

FIG. 16 is a perspective view of another embodiment of a rear derailleurwith a resistance control lever in a first position;

FIG. 17 is a perspective view of the rear derailleur shown in FIG. 16with the resistance control lever in a second position;

FIG. 18 is a partially exploded view of the movable member and theresistance control mechanism;

FIG. 19 is a perspective view of a particular embodiment of a cammounting unit;

FIG. 20 is a perspective view of a particular embodiment of an initialsetting cam;

FIG. 21 is a perspective view of a particular embodiment of a controlcam;

FIG. 22 is a perspective view of a particular embodiment of a controllever;

FIG. 23 is a schematic diagram of an alternative embodiment of aresistance control mechanism;

FIG. 24 is a side view of another embodiment of the movable member;

FIG. 25 is a flow chart describing the operation of the cam shown inFIG. 25; and

FIG. 26 is a side view of another embodiment of the movable member.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 shows a bicycle 10 comprising a frame 14 with front and rearwheels 18 and 22 rotatably coupled to frame 14 in a conventional manner.A front derailleur 26 is mounted to a seat tube 14 a of frame 14, and arear derailleur 30 is mounted to the rear of frame 14. Front derailleur26 switches a chain C among a plurality of front sprockets FS, and rearderailleur 30 switches chain C among a plurality of rear sprockets RS.Conventional shift control devices 34 and 38, mounted to a handlebar 42,are used to control the operation of front derailleur 26 and rearderailleur 30, respectively, through conventional Bowden cables 46 and50. Bicycle 10 is a conventional bicycle except for rear derailleur 30,so only rear derailleur 30 will be discussed in further detail.

As shown in FIG. 2, rear derailleur 30 comprises a base member 54, amovable member 58, a linkage assembly 62 and a chain guide 66. Basemember 54 is structured to be rotatably mounted to a rear derailleurmounting member 68 through a mounting bolt 70, and linkage assembly 62is coupled between base member 54 and movable member 58 so that chainguide 66 can move to a plurality of shift positions corresponding to thenumber of rear sprockets RS. Rear derailleur mounting member 68 isstructured to be fixedly mounted to the rear of frame 14 through amounting bolt 74. A return spring (not shown) biases movable member 58either laterally inwardly or laterally outwardly, depending upon theapplication, relative to the plurality of rear sprockets RS. In thisembodiment, the return spring biases movable member 58 laterallyoutwardly.

Linkage assembly 62 includes a pair of parallel links 78 and 82. Link 78is an upper/outer link, while link 82 is a lower/inner link. Links 78and 82 are pivotally coupled to base member 54 through pivot pins (notshown), and links 78 and 82 are pivotally coupled to movable member 58through pivot pins 86 and 90 (FIG. 3). A derailleur actuating arm 94extends rearwardly from a lower side of link 82. An outer casing 50 a ofBowden cable 50 is terminated at base member 54 in a conventionalmanner, and an inner wire 50 b of Bowden cable 50 is attached toactuating arm 94 in a conventional manner.

As shown in FIGS. 4 and 5, movable member 58 comprises a housing 98 anda link attachment portion 102. Housing 98 is fixedly attached to (e.g.,integrally formed with) link attachment portion 102 and houses a portionof a resistance applying element 106 that is discussed in further detailbelow. Link attachment portion 102 comprises a pair of tubular linkmounting ears 110 and 114 which have corresponding cylindrical openings118 and 122 for receiving respective pivot shafts 86 and 90 therein.

Housing 98 comprises a generally tubular portion 126, a plate guidingear 128 and a resistance element mounting flange 130. A radially innerportion of resistance element mounting flange 130 forms a mounting ledge134 having an inner peripheral surface 138 that defines a mounting bore142. A tubular bushing 146 is attached to the inner peripheral surface138 of mounting ledge 134 so as to be disposed within mounting bore 142.A tubular shaft bearing 150 is attached to mounting ledge 134 and totubular bushing 146. More specifically, shaft bearing 150 comprises atubular first section 154, a tubular second section 158, a radiallyoutwardly extending flange section 162, and a tubular mounting collar166. Second section 158 is disposed radially within and contacts tubularbushing 146. Flange section 162 extends radially outwardly at a junctionbetween first section 154 and second section 158, and mounting collar166 extends axially from the outer end of flange section 162 (to theright in FIG. 5). Mounting collar 166 surrounds and contacts mountingledge 134.

A pivot shaft 170 is disposed within shaft bearing 150. As shown inFIGS. 5 and 6, pivot shaft 170 includes a first portion 170 a, areduced-diameter second portion 170 b and a radially outwardly extendingretainer shoulder 170 c disposed at a junction between first portion 170a and second portion 170 b. First portion 170 a is disposed within shaftbearing 150, and second portion 170 b extends axially from resistanceelement mounting flange 130 (to the right in FIG. 5). A retainer washer174 is fitted between retainer shoulder 170 c and shaft bearing 150. Inthis embodiment, second portion 170 b of pivot shaft 170 forms part of aone-way clutch 178 of resistance applying element 106. Pivot shaft 170also includes a hexagonal tool-engaging opening 170 d on the right endthereof and a threaded inner peripheral surface 170 e on the left endthereof.

Chain guide 66 is mounted to pivot shaft 170 through a chain guideinterface shaft 182 and a chain guide mounting shaft 186 for rotationaround a rotational axis R. As shown in FIGS. 4 and 5, chain guide 66includes a first chain guide plate 190, a second chain guide plate 194,a guide pulley 198 rotatably supported between first chain guide plate190 and second chain guide plate 194 by chain guide mounting shaft 186,and a tension pulley 202 rotatably supported between first chain guideplate 190 and second chain guide plate 194 by a pivot shaft 206 that isconnected to first chain guide plate 190 and to second chain guide plate194. As shown in FIG. 5, chain guide interface shaft 182 includes a headportion 182 a and a threaded shaft portion 182 b. Threaded shaft portion182 b screws into the threaded inner peripheral surface 170 e of pivotshaft 170 so that pivot shaft 170 and chain guide interface shaft 182rotate together as an integral unit. Head portion 182 a has the form ofa three-step head including a first step portion 182 a′, a second stepportion 182 a″ and a third step portion 182 a′″. First step portion 182a′ functions as a spacer between guide pulley 198 and second chain guideplate 194, and second step portion 182 a″ fixedly supports second chainguide plate 194. Second chain guide plate 194 includes an arcuate guideslot 194 a that receives a threaded shaft 210 and a bearing nut 214therein. Threaded shaft 210 extends axially from plate guiding ear 128of tubular portion 126 of housing 98. Third step portion 182 a′″supports a cap member 216 that helps to prevent contaminants fromentering tubular portion 126 of housing 98. Finally, head portion 182includes a threaded inner peripheral surface 182 a″″.

Chain guide mounting shaft 186 includes a head portion 186 a with ahexagonal tool-engaging opening 186 b, an intermediate pivot shaftportion 186 c and a threaded end portion 186 d. Head portion 186 afixedly supports first chain guide plate 190, and intermediate pivotshaft portion 186 c rotatably supports guide pulley 198. Threaded endportion 186 d screws into the threaded inner peripheral surface 182 a″of chain guide interface shaft 182 so that pivot shaft 170, chain guideinterface shaft 182, chain guide mounting shaft 186, first chain guideplate 190 and second chain guide plate 194 rotate together as anintegral unit. A coil spring 217 has a first end mounted to resistanceelement mounting flange 130 and a second end mounted to second chainguide plate 194 to bias chain guide 66 in the clockwise direction andthereby take up slack in chain C.

As shown in FIGS. 7-10, resistance applying element 106 includes one-wayclutch 178 and a friction applying member 218. One-way clutch 178applies resistance to rotational movement of chain guide 66 in apredetermined direction, and friction applying member 218 appliesfrictional resistance to rotational movement of chain guide 66 byapplying frictional resistance to the rotation of one-way clutch 178. Aprotective cover 224 is mounted to resistance element mounting flange130 through screws 225 to protect the enclosed components from theoutside environment.

As shown in FIGS. 6 and 9-12, one-way clutch 178 comprises an innermember in the form of second portion 170 b of pivot shaft 170, an outermember 226, a plurality of rollers 230 and a roller retainer 234. Thus,in this embodiment, one-way clutch 178 is a roller clutch. As shown moreclearly in FIG. 11, second portion 170 b of pivot shaft 170 has a smoothcircular outer peripheral surface 170 f for supporting the plurality ofrollers 230. On the other hand, outer member 226 has an inner peripheralsurface 226 a and a plurality of cam ramps 226 b that extend radiallyoutwardly from inner peripheral surface 226 a. Each cam ramp 226 b isassociated with one of the plurality of rollers 230.

Roller retainer 234 is made from a synthetic resin, and it positionseach of the plurality of rollers 230 in the proper circumferentialposition relative to an associated cam ramp 226 b and also biases eachof the plurality of rollers 230 towards the radially inner portion ofits associated cam ramp 226 b. As shown in FIG. 12, roller retainer 234includes an upper retainer ring 238, a lower retainer ring 242, aplurality of retainer columns 246 and a spring assembly 250. Theplurality of retainer columns 246 are disposed between and are connectedto upper retainer ring 238 and lower retainer ring 242 to form aplurality of roller receiving spaces 254.

As shown in FIGS. 11 and 12, each retainer column 246 has a generallyreversed L-shaped cross section that forms a spring space 262 betweenthe retainer column and its associated roller 230. Each retainer column246 includes a generally rectangular, circumferentially-directedrotation stopping projection 258 that engages inner peripheral surface226 a of outer member 226 to prevent reverse rotation of roller retainer234 (counterclockwise in FIG. 11) relative to outer member 226. Lowerretainer ring 242 includes additional projections 266 that engagecorresponding recesses (not shown) in outer member 226 to nonrotatablylock roller retainer 234 to outer member 226.

FIG. 12 shows roller retainer 234 in an assembled state immediatelyprior to the final fastening of spring assembly 250 to upper retainerring 238. In this embodiment, spring assembly 250 comprises a thindisc-shaped top plate 270 and a plurality of circumferentially disposedleaf springs 274. Top plate 270 fits within a shape-conforming recessedsurface 275 formed at the top of upper retainer ring 238. Top plate 270includes a central opening 282 that aligns with a central opening 286formed in upper retainer ring 238, a plurality of circumferentiallydisposed fastener openings 290, and a plurality of spring retaining arms294 that extend radially outwardly and in a circumferential direction.Each spring retaining arm 294 is attached to (e.g., integrally formedwith) a corresponding leaf spring 274 that extends downwardly through acorresponding spring opening 298 in upper retainer ring 238. The leafspring then extends into a corresponding spring space 262 to bias acorresponding roller 230 (in the counterclockwise direction in FIG. 11).A plurality of fastener posts 300 formed on upper retainer ring 238extend through the plurality of fastener openings 290 formed in topplate 270. Fastener posts 300 are flattened after assembly as shown at300′ to form rivets that fasten top plate 270 to upper retainer ring238. As a result, upper retainer ring 238, lower retainer ring 242, theplurality of retainer columns 246 and the plurality of fastener posts300 are one-piece.

One-way clutch 178 operates in the following manner. When pivot shaft170 rotates in the clockwise direction in FIG. 11, then the plurality ofrollers 230 move to the radially outer portions of the plurality of camramps 226 b against the biasing forces leaf springs 274. As a result,pivot shaft 170 rotates freely in the clockwise direction relative toouter member 226. On the other hand, when pivot shaft 170 rotates in thecounterclockwise direction, then the plurality of rollers 230 move tothe radially inner portions of the plurality of cam ramps 226 b inaccordance with the biasing forces of leaf springs 274. As a result,pivot shaft 170 is nonrotatably coupled to outer member 270 so thatpivot shaft 170 and outer member 270 rotate together as a unit.

As shown in FIGS. 9 and 10, friction applying member 218 comprises afriction-applying portion 218 a and two movable end portions 218 b and218 c. In this embodiment, friction-applying portion 218 a extendscircumferentially along the outer peripheral surface of outer member 226of one-way clutch 178, and movable end portions 218 b and 218 c extendradially outwardly from opposite ends of friction-applying portion 218a. Friction-applying portion 218 a has a band shape with a widthapproximately equal to the width of outer member 226 of one-way clutch178. Friction applying member 218 is an elastic member such as a springmember that may be is made from a metal or alloy.

A resistance control unit 310 is provided to control the amount ofresistance applied to pivot shaft 170 and chain guide 66 by resistanceapplying element 106. In this embodiment, resistance control unit 310comprises resistance control elements such as an initial setting cam314, a control cam 326 and a control lever 330. Initial setting cam 314is rotatably mounted to resistance element mounting flange 130 through ashaft 318. Initial setting cam 314 is positioned to contact movable endportion 218 b of friction applying member 218. Initial setting cam 314has a cam surface 314 a that includes a radially inner cam surface 314 band a radially outer cam surface 314 c. In this embodiment, radiallyinner cam surface 314 b gradually tapers radially outwardly to radiallyouter cam surface 314 c, but cam surface 314 a could be stepped or haveany other radially changing surface depending upon the application.Preferably, cam surface 314 a includes a plurality of surfaces so thatthe rotational position of initial setting cam 314 is maintained duringuse of rear derailleur 30. Such surfaces could result from the gradualtransition from radially inner cam surface 314 b to radially outer camsurface 314 c. Alternatively, the surfaces could result from flattenedor recessed surfaces on cam surface 314 a (such as at radially inner camsurface 314 b and radially outer cam surface 314 c). Such surfaces couldbe sufficient to index initial setting cam 314 in predeterminedpositions so that distinctly more force is required to rotate initialsetting cam 314 away from the indexed position. In this embodiment,initial setting cam 314 is non-rotatably but detachably mounted to shaft316. Shaft 316 includes an undulating or otherwise splined surface sothat the orientation of initial setting cam 314 may be adjusted byremoving initial setting cam 314 from shaft 316, rotating initialsetting cam 314 to a desired position, and then attaching initialsetting cam 314 to shaft 316 in the new rotational position.

Control cam 326 and control lever 330 are disposed at movable endportion 218 c of friction applying member 218, wherein control cam 326is non-rotatably coupled relative to control lever 330 by a couplingshaft 334. Coupling shaft 334 passes through resistance element mountingflange 130 so that control lever 330 is disposed outside of movablemember 58. As a result, control lever 330 can be manipulated by a userwithout removing protective cover 224.

Control cam 326 is positioned to contact movable end portion 218 c offriction applying member 218. Control cam 326 has a cam surface 326 athat includes a radially inner cam surface 326 b and a radially outercam surface 326 c. In this embodiment, radially inner cam surface 326 bgradually tapers radially outwardly to radially outer cam surface 326 cin a non-linear manner, but cam surface 326 a could be stepped or haveany other radially changing surface depending upon the application. Forexample, cam surface 326 a could include a plurality of surfaces so thatthe rotational position of control cam 314 is maintained during use ofrear derailleur 30. Such surfaces could result from the gradualtransition from radially inner cam surface 326 b to radially outer camsurface 326 c. Alternatively, the surfaces could result from flattenedor recessed surfaces on cam surface 326 a (such as at radially inner camsurface 326 b and radially outer cam surface 326 c). Such surfaces couldbe sufficient to index control cam 326 in predetermined positions sothat distinctly more force is required to rotate control cam 326 awayfrom the indexed position.

-   -   As shown in FIGS. 7 and 9, coupling shaft 334 comprises an inner        cylindrical shaft core 334 a disposed within a coupling member        334 b. Coupling member 334 b has a splined outer peripheral        surface 334 b′, a tubular section 334 b″ and a mounting ear 334        b′″. Splined outer peripheral surface 334 b′ engages a splined        inner peripheral surface 326 d of control cam 326 so that        control cam 326 and coupling shaft 334 rotate together as a        unit. Control cam 326 is detachable from coupling shaft 334.        Thus, the rotational position of control cam 326 relative to        coupling shaft 334 may be adjusted in the same manner as initial        setting cam 314. Tubular section 334 b″ passes through        resistance element mounting flange 130 so that coupling shaft        334 can rotate relative to resistance element mounting flange        130. Mounting ear 334 b′″ extends generally perpendicularly from        tubular section 334 b″ and radially outwardly from shaft core        334 a.

As shown more clearly in FIG. 7, control lever 330 comprises a shaftmounting portion 330 a, a radially outwardly extending portion 330 b anda finger contact portion 330 c. Shaft mounting portion 330 a has a firstopening 330 a′ and a second opening 330 a″, wherein first opening 330 a′receives shaft core 334 a therein, and second opening 330 a″ receives afastener 338 therein for rigidly and nonrotatably attaching controllever 330 to coupling member 334 b of coupling shaft 334. Control lever330 is detachable from coupling shaft 334 when fastener 338 is removed.Control lever 330 may be made from metal (e.g., aluminum) or syntheticresin. Shaft core 334 a and coupling member 334 b may be formed asone-piece and/or control lever 330 and coupling shaft 334 may be formedas one-piece. Radially outwardly extending portion 330 b extendsradially outwardly from shaft core 334 a and fastener 338, and fingercontact portion 330 c is disposed at the end of radially outwardlyextending portion 330 b. Finger contact portion 330 c extends generallyperpendicularly from radially outwardly extending portion 330 b to forma generally rectangular finger paddle that is disposed in closeproximity to resistance element mounting flange 130. As shown moreclearly in FIGS. 7 and 8, finger contact portion 330 c includes athreaded bore 330 c′ that houses an indexing ball 342 and an indexingspring (not shown). The indexing spring and indexing ball 342 aremaintained within bore 330 c′ by an adjustment screw 346 that may beused to adjust the spring force against indexing ball 342.Alternatively, ball 342 may be formed from an elastic resin such that apart of ball 342 is disposed in an unthreaded bore 330′ or otherwisebonded on finger contact portion 330 c.

Resistance element mounting flange 130 forms a pair of indexingprojections 130 a with an indexing recess 130 b therebetween. Whencontrol lever 330 is in the position shown in FIGS. 9 and 10, indexingball 342 is disposed within indexing recess 130 b to index control lever330 in that position. In other words, control lever 330 is stablymaintained in that position so that distinctly more force is required torotate control lever 330 away from that position. Resistance elementmounting flange 130 also forms an indexing abutment 130 c and anindexing surface 130 d. Indexing abutment 130 c and indexing surface 130d cooperate with indexing ball 342 to index control lever 330 in theposition shown in FIGS. 14 and 15. More specifically, indexing abutment130 c contacts finger contact portion 330 c of control lever 330 tolimit counterclockwise rotation of control lever 330, and indexingsurface 130 d has a temporarily increasing radius of curvatureimmediately to the right of indexing ball 342 (when control lever 330 isdisposed in the position shown in FIGS. 14 and 15) so that the indexingspring must be further compressed in order to rotate control lever 330clockwise. Thus, distinctly more force is required to rotate controllever 330 clockwise away from the position shown in FIGS. 14 and 15. Inanother embodiment, radially outer cam surface 326 c may index controllever 330 instead of indexing abutment 130 c and indexing surface 130 d.In such an embodiment, when movable end portion 218 c of frictionapplying member 218 moves from radially inner cam surface 326 b toradially outer cam surface 326 c, or from radially outer cam surface 326c to radially inner cam surface 326 b, the surfaces create an audibleand/or tactile clicking sensation.

In operation, control lever 330 is rotated to the position shown inFIGS. 8-10 so that indexing ball 342 is disposed within indexing recess103 b and a radially inner portion of cam surface 326 a of control cam326 contacts movable end portion 218 c of friction applying member 218.Alternatively, it is possible that radially inner portion of cam surface326 a of control cam 326 does not contact movable end portion 218 c offriction applying member 218 when indexing ball 342 is disposed withinindexing recess 103 b. Then, protective cover 224 is removed, andinitial setting cam 314 is rotated so that movable end portions 218 band 218 c of friction applying member 218 are disposed at desiredpositions to adjust the diameter of friction applying portion 218 a offriction applying member 218 to apply a desired initial frictional forceto outer member 226 of one-way clutch 178. For example, initial settingcam 314 could be set so that radially inner cam surface 314 b contactsmovable end portion 218 b, wherein radially inner cam surface 314 b hasa radius such that friction applying portion 218 a does not applyoperatively noticeable friction to outer member 226 of one-way clutch178. As a result, one-way clutch 178 rotates freely in both theclockwise and counterclockwise directions, and no additional resistanceis applied to the rotation of chain guide 66 in either the clockwise orthe counterclockwise direction other than the resistance applied by coilspring 217. Protective cover 224 is re-attached after initial settingcam 314 is set to the desired position.

Normally, however, initial setting cam 314 is set so that a radiallyouter portion of cam surface 314 a causes movable end portion 218 b tomove toward movable end portion 218 c. As a result, the diameter offriction applying portion 218 a of friction applying member 218 isreduced to apply light or moderate friction to outer member 226 ofone-way clutch 178. Thus, when chain guide 66 rotates clockwise to takeup the slack in chain C, rollers 230 in one-way clutch 178 move to theradially outer portions of cam ramps 226 b, no resistance is applied tothe rotation of pivot shaft 170, and chain guide 66 rotates freely inthe clockwise direction. On the other hand, when chain guide 66 attemptsto rotate in the counterclockwise direction as a result of rough riding,the counterclockwise rotation of pivot shaft 170 causes rollers 230 inone-way clutch 178 to move toward the radially inner portions of camramps 226 b, thereby locking pivot shaft 170 to outer member 226 so thatpivot shaft 170 and outer member 226 rotate as a unit. However, due tothe friction applied by friction applying member 218 to outer member226, counterclockwise rotation of outer member 226 and pivot shaft 170is resisted, thereby causing resistance to counterclockwise rotation ofchain guide 66.

If the rider expects to be riding in very severe terrain, thenadditional resistance to counterclockwise rotation of chain guide 66 maybe desired. To accommodate such riding, control lever 330 is rotated tothe position shown in FIGS. 13-15. The radially outer portion of camsurface 326 a of control cam 326 presses movable end portion 218 c offriction applying member 218 to the left, thereby further reducing thediameter of friction applying portion 218 a of friction applying member218 and increasing the frictional force applied by friction applyingmember 218 to outer member 226 of one-way clutch 178. The increasedfrictional force applied by friction applying member 218 to outer member226 of one-way clutch 178 further increases the resistance tocounterclockwise rotation of pivot shaft 170 and chain guide 66 withoutaffecting the clockwise rotation of chain guide 66.

FIGS. 16-22 illustrate another embodiment of a rear derailleur 30′ withrotation resistance. This embodiment is the same as the embodiment shownin FIGS. 1-15 except that a control lever 350 for controlling thefrictional force applied by friction applying member 218 to outer member226 of one-way clutch 178 is mounted to the outside of a protectivecover 224′. FIG. 16 shows control lever 350 in a first positioncorresponding to control lever 330 in FIGS. 8-10, and FIG. 17 showscontrol lever 350 in a second position corresponding to control lever330 in FIGS. 13-15. The operation is the same as in the first embodimentexcept as otherwise noted. Thus, only the difference between thisembodiment and the first embodiment will be described in detail.

FIG. 18 is a partially exploded view of a movable member 58′ and aresistance control mechanism 354 for this embodiment. A resistanceelement mounting flange 130′ has the same structure as resistanceelement mounting flange 130 in the first embodiment except for anoval-shaped mounting recess 358 that is substituted for the opening forcoupling shaft 334 in the first embodiment. Mounting recess 358 is usedto attach resistance control unit 354.

As shown in FIGS. 18-22, resistance control unit 354 comprises amounting bracket 362, an initial setting cam mounting shaft 366 attachedto one end of mounting bracket 362, an initial setting cam 370 mountedto initial setting cam mounting shaft 366, a control cam mounting shaft374 attached to the other end of mounting bracket 362, a control cam 378rotatably mounted to control cam mounting shaft 374, and control lever350 spline-connected to control cam 378. More specifically, control cam378 includes a plurality of splines 386 that engage a complementaryplurality of splines 390 disposed in a cam mounting portion 350 a ofcontrol lever 350 so that control cam 378 and control lever 350 rotateas a unit around control cam mounting shaft 374. Control cam 378 furtherincludes a bearing portion 394 that engages an opening (not shown) inprotective cover 224′ so that splines 386, and hence control lever 350,are disposed outside of protective cover 224′. Control lever 350 furtherincludes a radially extending portion 350 b and a generally cylindricalfinger contact portion 350 c that extends perpendicularly from radiallyextending portion. Initial setting cam 370 is detachable from initialsetting cam mounting shaft 366 so that the orientation of initialsetting cam 370 may be adjusted by removing initial setting cam 370 frominitial setting cam mounting shaft 366, rotating initial setting cam 370to a desired position, and then attaching initial setting cam 370 toinitial setting cam mounting shaft 366 in the new rotational position.

In this embodiment, control cam 378 includes a first surface 378 a and asecond surface 378 b that engage movable end portion 218 c of frictionapplying member 214. First surface 378 a and second surface 378 b areflattened surfaces that cooperate with movable end portion 218 c offriction applying member 284 to index control cam 378, and hence controllever 350, in first and second indexed positions corresponding to twoavailable resistances that resist counterclockwise rotation of chainguide 66. Thus, indexing surfaces on resistance element mounting flange130′ are not required in this embodiment.

While the above is a description of various embodiments of inventivefeatures, further modifications may be employed without departing fromthe spirit and scope of the present invention. For example, whilecontrol levers 330 and 350 were used to select desired resistances torotation of chain guide 66, other manually operated members that do notrequire tools, such as knobs, may be used. While control levers 330 and350 were mounted at their respective movable members 58 and 58′, such aconfiguration is not necessary. As shown in FIG. 23, a control lever 398or other manually-operated member could be mounted to handlebar 42 or tosome other structure, and control lever 398 could be coupled to acontrol lever or control disk mounted to the movable member through acontrol cable such as a Bowden cable 400, wherein the control lever/diskis operatively mounted to the control cam. Friction applying member 218,a part of resistance control unit 310 and one way clutch 178 may bedisposed in housing 98 of movable member 58. While the control leverswere shown as being located at the laterally inner or outer surfaces ofthe movable member and cover, the control lever could be disposedanywhere between the laterally inner and outer surfaces defined by themovable member, including any provided cover, such as between planes P1and P2 in FIG. 3.

FIG. 24 is a side view of another embodiment of movable member 58. Inthis embodiment, a force sensor 410 (e.g., a pressure sensor) isdisposed between initial setting cam 314 (which functions as a forcevarying cam in this embodiment) and movable end portion 218 b offriction applying member 218, and cam 314 is mounted to an output shaft414 of a motor 418. Thus, cam 314 engages movable end portion 218 b offriction applying member 218 indirectly through force sensor 410 toapply a force to friction applying member 218 that is non-parallel torotational axis R, and force sensor 410 senses the force applied by cam314 to friction applying member 218. In this embodiment, motor 418 iscontrolled by a regulating circuit 422 (FIG. 1) in the form of a cyclecomputer mounted to handlebar 42. If desired, regulating circuit 422 maybe disposed on the rear derailleur. Cam 314, force sensor 410, motor 418and regulating circuit 422 constitute an example of a resistance controlelement that prevents a reduction in the resistance to rotationalmovement of chain guide 66 applied by resistance applying element 106.More specifically, regulating circuit 422 varies the force applied bycam 314 to friction applying member 218 in response to the force sensedby force sensor 410. As a result, cam 314, force sensor 410, motor 418and regulating circuit 422 vary the resistance applied to one-way clutch178 by friction applying member 218, and it does so without any manualoperations (e.g., automatically).

FIG. 25 is a flowchart that describes the operation of this embodiment.Regulating circuit 422 initially obtains a value of the force F sensedby force sensor 410 in a step 430. It is then determined in a step 434whether the force F is less than or equal to a lower force thresholdvalue F1 stored in a memory in regulating circuit 422 or otherwisecalculated by regulating circuit 422. If so, then regulating circuit 422provides signals to motor 418 in a step 438 to rotate cam 314counterclockwise, thereby increasing the force applied by cam 314 tomovable end portion 218 b of friction applying member 218. Thereafter,the process loops back to step 430. If it is determined in step 434 thatforce F is not less than or equal to threshold value F1, it is thendetermined in a step 442 whether force F is greater than or equal to ahigher force threshold value F2. If so, then regulating circuit 422provides signals to motor 418 in a step 446 to rotate cam 314 clockwise,thereby decreasing the force applied by cam 314 to movable end portion218 b of friction applying member 218. Thereafter, the process loopsback to step 430. If it is determined in step 442 that force F is notgreater than or equal to threshold value F2, then the force applied bycam 314 to movable end portion 218 b of friction applying member 218 isin the desired range F1<F<F2, and the process loops back to step 430.

FIG. 26 is a side view of another embodiment of movable member 58 thatincludes another embodiment of a resistance control element thatprevents a reduction in the resistance to rotational movement of chainguide 66 applied by resistance applying element 106. In this embodiment,initial setting cam 314 is replaced by a spring 450 that has spring ends450 a and 450 b, wherein spring end 450 a engages an abutment 58 a ofmovable member 58, and spring end 450 b engages movable end portion 218b of friction applying member 218 to apply a force to friction applyingmember 218 that is non-parallel to rotational axis R. In thisembodiment, spring 450 is a coil spring under compression so that spring450 pushes movable end portion 218 b towards movable end portion 218 c.Spring 450 constitutes another example of a resistance control elementthat applies a variable force to resistance applying element 106 withoutany manual operations (e.g., automatically).

The size, shape, location or orientation of the various components maybe changed as desired. Components that are shown directly connected orcontacting each other may have intermediate structures disposed betweenthem. Separate components may be combined, and vice versa. The functionsof one element may be performed by two, and vice versa. The function ofone element may be performed by another, and functions may beinterchanged among the elements. The structures and functions of oneembodiment may be adopted in another embodiment. It is not necessary forall advantages to be present in a particular embodiment at the sametime. Every feature which is unique from the prior art, alone or incombination with other features, also should be considered a separatedescription of further inventions by the applicant, including thestructural and/or functional concepts embodied by such feature(s). Termsof degree such as “substantially,” “about” and “approximately” as usedherein include a reasonable amount of deviation of the modified termsuch that the end result is not significantly changed. Thus, the scopeof the invention should not be limited by the specific structuresdisclosed or the apparent initial focus or emphasis on a particularstructure or feature.

What is claimed is:
 1. A bicycle derailleur comprising: a base member adapted to be mounted to a bicycle; a movable member movably coupled to the base member; a chain guide coupled to the movable member for rotation around a rotational axis; a resistance applying element that applies resistance to rotational movement of the chain guide; and a resistance control element that applies a force to the resistance applying element in a direction that is non-parallel with the rotational axis, without any manual operations, to prevent a reduction in the resistance to rotational movement of the chain guide applied by the resistance applying element.
 2. The derailleur according to claim 1 wherein the resistance control element comprises a spring member.
 3. The derailleur according to claim 1 wherein the resistance control element comprises a cam member.
 4. The derailleur according to claim 1 wherein the resistance control element comprises: a force sensor that senses a force applied by the resistance control element to the resistance applying element; and a regulating circuit that varies the force applied by the resistance control element to the resistance applying element in response to the force sensed by the force sensor.
 5. The derailleur according to claim 4 wherein the resistance control element further comprises a cam member.
 6. The derailleur according to claim 5 wherein the resistance control element further comprises a motor that rotates the cam member in response to signals from the regulating circuit.
 7. The derailleur according to claim 1 wherein the resistance applying element comprises a friction applying member that applies frictional resistance to rotational movement of the chain guide.
 8. The derailleur according to claim 7 wherein the friction applying member comprises a first spring member.
 9. The derailleur according to claim 8 wherein the first spring member extends circumferentially about the rotational axis and has a first movable end portion and a second movable end portion.
 10. The derailleur according to claim 9 wherein the resistance control element engages the first movable end portion of the first spring member.
 11. The derailleur according to claim 10 wherein the resistance control element comprises a second spring member.
 12. The derailleur according to claim 11 further comprising a cam member that engages the second movable end portion of the first spring member.
 13. The derailleur according to claim 12 wherein the cam member is manually operated.
 14. The derailleur according to claim 10 wherein the resistance control element comprises a first cam member.
 15. The derailleur according to claim 14 wherein the resistance control element comprises: a force sensor that senses a force applied by the resistance control element to the resistance applying element; and a regulating circuit that varies the force applied by the resistance control element to the resistance applying element in response to the force sensed by the force sensor.
 16. The derailleur according to claim 15 wherein the resistance control element further comprises a motor that rotates the first cam member.
 17. The derailleur according to claim 16 further comprising a second cam member that engages the second movable end portion of the first spring member.
 18. The derailleur according to claim 17 wherein the second cam member is manually operated.
 19. A bicycle derailleur comprising: a base member adapted to be mounted to a bicycle; a movable member movably coupled to the base member; a chain guide coupled to the movable member for rotation around a rotational axis; a resistance applying element that applies resistance to rotational movement of the chain guide; and a resistance control element that automatically applies a variable force to the resistance applying element; wherein the resistance control element applies the variable force to the resistance applying element in a direction that is non-parallel with the rotational axis.
 20. The apparatus according to claim 19 wherein the resistance control element includes a spring element.
 21. A bicycle derailleur comprising: a base member adapted to be mounted to a bicycle; a movable member movably coupled to the base member; a chain guide coupled to the movable member for rotation around a rotational axis; a resistance applying element that applies resistance to rotational movement of the chain guide; and a resistance control element that automatically applies a variable force to the resistance applying element, wherein the resistance control element includes a sensor that senses the force applied to the resistance applying element, and wherein the resistance control element automatically applies the variable force to the resistance applying element in response to the force sensed by the sensor.
 22. The derailleur according to claim 21 wherein the resistance control element further includes a regulating circuit operatively coupled to the sensor so that the regulating circuit controls the force applied to the resistance applying element in response to the force sensed by the sensor.
 23. The derailleur according to claim 22 wherein the resistance applying member comprises a spring member.
 24. The derailleur according to claim 23 wherein the resistance control element further includes: a cam operatively coupled to the spring member; and a motor operatively coupled to the regulating circuit and to the cam so that the motor moves the cam in response to the force sensed by the sensor.
 25. The derailleur according to claim 24 wherein the spring member extends circumferentially about the rotational axis and has a movable end portion, and wherein the cam applies a force to the movable end portion. 